Renal diseases are often discovered accidently during routine urinalysis. To test the diagnostic value of screening for renal disease by urinalysis, a cross-sectional study was conducted in two major Primary Health Care Centers (PHCCs) in Abha, Saudi Arabia, on patients attending these PHCCs with different medical problems. A total of 10,500 patients visited the two PHCCs during the study period between January 1994 and September 1994, and 1,006 urine samples were examined. Patients known to have renal diseases, pregnant women and menstruating women were excluded from the study. There were 390 males (38.8%) with a mean age of 30.9 + 18.3 years (range 1 - 78 years) and 616 females (61.2%) with a mean age of 28.7 ± 13.9 years (range 2 - 87 years). Proteinuria was present in 12.8% of the males and 11.0% of the females. Pyuria was present more significantly in females (25%) than in males (9.5%) with a p value of 0.0001. This study shows a high prevalence of abnormal urinalysis in a country where most patients present late with advanced renal disease of unknown cause. Also, such a screening test at the PHCC level is cost-effective.